In 1993, the W.M. Keck Foundation awarded the first grant to UW-Madison to establish a Laboratory for Biological Imaging (www.keck.bioimaging.wisc.edu). The Laboratory acquired a Bio-Rad MRC 1024 confocal microscope, and began immediately to offer investigators from across the UW campus the opportunity to incorporate confocal imaging in their research. Eleven years later, with an award from NCRR, the Laboratory added a Bio-Rad Radiance 2100 MP confocal/multiphoton microscope, making open source multiphoton microscopy available for the first time at the UW-Madison. In the last 12 months alone, nearly 60 laboratories at UW-Madison, representing approximately 20 broad research areas in the biological sciences, have used the Laboratory's microscopes. Now the Laboratory wishes to replace its original Bio-Rad microscope with a new microscope. While the MRC-1024 has been a capable instrument for 15 years, it now needs repairs almost monthly, and compounding this problem is Carl Zeiss's decision not to offer a service contract for the MRC- 1024 after September of last year. In addition, the MRC-1024 is obsolete by contemporary standards. This is reflected by a reduction of over 60% in usage of the MRC-1024 during the past 12 months, as the Laboratory's users shift their work to the Radiance 2100 MP. Unfortunately, the Radiance cannot accommodate all of those who wish to use it, creating significant delays for some users. In addition, many users operate the Radiance 2100 MP solely for confocal imaging, compromising the microscope's primary role as a multiphoton instrument. In selecting a replacement for the MRC-1024, microscopes from Leica Microsystems (TCS SP5), Nikon (Eclipse C1Plus), Zeiss (LSM 510 META ) and Olympus (FluoView FV1000) were evaluated to determine which instrument would be the best suited for operation in a multi-user imaging laboratory. After comparing each of the systems mentioned, working directly with each, and reviewing their reliability and service records, we have concluded that the Olympus FluoView FV1000 offers the best balance of flexibility, ease of use, and performance for operating in a Laboratory that serves investigators with a diverse range of research projects and experience. The FV1000 requested will be equipped with six laser lines, two standard PMT collection channels, and two spectral detectors. The spectral detectors will enable users to unmix spectrally overlapping signals, a powerful tool for reducing interference by caused by autofluorescence. Separating spectrally overlapped signals also will provide increased flexibility in designing experiments e.g., using eGFP and eYFP in the same experiment, or in imaging simultaneously multiple fluorophores. PUBLIC HEALTH RELEVANCE: This application request funds to purchase a new confocal microscope that will be used by eight biomedical research scientists. Seven of these scientists will use the microscope to study processes that are involved in various diseases such as cancer, anemia, and cardiac aging. The remaining scientist will employ the microscope to study how growing axons in the embryonic brain make proper connections to ensure normal brain development.